Pinpoint Test Q: The Blower Motor Is Inoperative - EMTC
Climate Control System
Pinpoint Tests
Pinpoint Test Q: The Blower Motor is Inoperative - EMTC
Refer to Wiring Diagram Set 54, Manual Climate Control System for schematic and connector information. Diagrams By Number
Normal Operation
Under normal operation, the blower motor relay coil receives voltage. The coil receives ground from the HVAC module - Electronic Manual Temperature Control (EMTC) if any function selector position but OFF is selected. Voltage is supplied to the relay switch contact. When the relay coil is energized, voltage is delivered to the blower motor. Ground for the blower motor is provided from the blower resistor or the blower switch (HI). The blower resistor and blower switch are grounded.
This pinpoint test is intended to diagnose the following:
- Fuse(s)
- Wiring, terminals or connectors
- HVAC module - EMTC
- Blower motor
- Blower motor relay
- Blower motor switch
PINPOINT TEST Q: THE BLOWER MOTOR IS INOPERATIVE - EMTC
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Q1 CHECK CIRCUIT (BK/RD) FOR GROUND
- Ignition OFF.
- Disconnect: Blower Motor C288.
- Turn the function selector switch to the PANEL position.
- Turn the blower motor switch to the HI position.
- Measure the resistance between A/C blower motor C288-1, circuit (BK/RD), harness side and ground.
- Is the resistance less than 5 ohms?
Yes
GO to Q4.
No
GO to Q2.
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Q2 CHECK CIRCUIT CH430 (VT/OG)/(BK/RD) FOR AN OPEN
- Disconnect: Blower Motor Switch C2357B.
- Measure the resistance between blower motor switch C2357B-2, circuit CH430 (VT/OG), harness side and blower motor C288-1, circuit (BK/RD), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to Q3.
No
REPAIR circuit CH430 (VT/OG)/(BK/RD) for an open. TEST the system for normal operation.
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Q3 CHECK CIRCUIT GD116 (BK/VT) FOR AN OPEN
- Measure the resistance between blower motor switch C2357B-3, circuit GD116 (BK/VT), harness side and ground.
- Is the resistance less than 5 ohms?
Yes
INSTALL a new blower motor switch. TEST the system for normal operation.
No
REPAIR circuit GD116 (BK/VT) for an open. TEST the system for normal operation.
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Q4 CHECK A/C BLOWER MOTOR CIRCUIT (BK) FOR VOLTAGE
- Ignition ON.
- Measure the voltage between A/C blower motor connector C288-1, circuit (BK), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
INSTALL a new blower motor. TEST the system for normal operation.
No
GO to Q5.
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Q5 CHECK CIRCUIT CH402 (YE/GN)/(BK) FOR AN OPEN
- Ignition OFF.
- Disconnect: Blower Motor Relay.
- Measure the resistance between blower motor relay socket, circuit CH402 (YE/GN) and blower motor C288-1, circuit (BK), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to Q6.
No
REPAIR circuit CH402 (YE/GN)/(BK) for an open. TEST the system for normal operation.
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Q6 CHECK THE BLOWER MOTOR RELAY
- Connect: Blower Motor C288.
- Ignition ON.
- Connect a fused jumper lead between blower motor relay socket, circuits CH402 (YE/GN) and CBP45 (YE).
- Does the blower motor operate?
Yes
GO to Q7.
No
VERIFY Battery Junction Box (BJB) fuse 66 (40A) is OK. If OK, REPAIR circuit CH402 (YE/GN) for an open. TEST the system for normal operation.
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Q7 CHECK THE RELAY COIL SUPPLY VOLTAGE
- Measure the voltage between blower motor relay socket, circuit CBP45 (YE) and ground.
- Is the voltage greater than 10 volts?
Yes
GO to Q8.
No
VERIFY Smart Junction Box (SJB) fuse 45 (5A) is OK. If OK, REPAIR circuit CBP45 (YE) for an open. TEST the system for normal operation.
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Q8 CHECK THE BLOWER MOTOR RELAY
NOTICE: The following step uses a test light to simulate normal circuit loads. Use only the test light recommended in the Special Tools table at the beginning. To avoid connector terminal damage, use the Flex Probe Kit for the test light probe connection to the vehicle. Do not use the test light probe directly on any connector.
- Connect a 12-volt test light between blower motor relay socket, circuits CH123 (VT/GN) and CBP45 (YE).
- Does the test light illuminate?
Yes
INSTALL a new blower motor relay. TEST the system for normal operation.
No
GO to Q9.
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Q9 CHECK CIRCUIT CH123 (VT/GN) FOR AN OPEN
- Ignition OFF.
- Disconnect: HVAC - Module EMTC C2357A.
- Measure the resistance between and blower motor relay socket, circuit CH123 (VT/GN) HVAC module - EMTC C2357A-24, circuit CH123 (VT/GN), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to Q10.
No
REPAIR circuit CH123 (VT/GN) for an open. TEST the system for normal operation.
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Q10 CHECK THE HVAC MODULE CONNECTION
- Inspect the HVAC module connectors for:
- corrosion.
- pushed-out terminals.
- damaged terminals.
- Connect and correctly seat all the HVAC module connectors.
- Clear the DTCs.
- Operate the system and verify the concern is still present.
- Is the concern still present?
Yes
INSTALL a new HVAC module. TEST the system for normal operation.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. TEST the system for normal operation.
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